Reword auth resolution section

drafts/erikj_federation.rst

@@ -132,12 +132,13 @@ chain for those auth events.
 Auth chain resolution
 ~~~~~~~~~~~~~~~~~~~~~
 
-**TODO**: If an auth check fails, or if we get told something we accepted
-should have been rejected, we need to try and determine who is right.
+If an auth check fails, or if we get told something we accepted should have
+been rejected, we need to try and determine who is right.
 
-Both should inform the other of what they think the current auth chain is. If
-either are missing auth events that they know are valid (through authorization
-and state resolution) they process the missing events as usual.
+If two servers disagree about the validity of the auth events, both should
+inform the other of what they think the current auth chain is. If either are
+missing auth events that they know are valid (through authorization and state
+resolution) they process the missing events as usual.
 
 If either side notice that the other has accepted an auth events we think
 should be rejected (for reasons *not* in their auth chain), that server should